1. Field of the Invention
The present invention relates to electrical switches, and more particularly, to switches used in computer keyboard applications.
2. Art Background
In the computing industry, it is quite common to enter data into a computer by means of a keyboard. Typically, the keyboard is comprised of a plurality of discrete switch assemblies coupled to a printed circuit board having circuit pathways or contacts thereon. Upon depressing or activating a switch disposed on the keyboard, an electrical contact is achieved and appropriate data is thereby entered by the user.
As a result of the heavy and continuous demand placed on keyboard switches by frequent use, switches assemblies of this type must be highly reliable and yet cost effective. Numerous attempts to achieve a low cost but reliable keyboard switch have been made in recent years. For example, U.S. Pat. No. 3,979,568 issued Sept. 7, 1976 discloses a keyboard switch assembly having a movable contact supported by helicline legs on a common conductive sheet. An electrical contact is disposed below the movable contact such that the depression by a user of the movable contact forces it to be physically adjacent to the electrical contact disposed below. If capacitive switching is used, the movable contact and the electrical contact need not actually physically touch. However, switches of this type do not achieve the desired cost goals because of the sophisticated electronics required to drive and sense capacitive switches. Mechanical contact switches of this type do not achieve the desired level of reliability since by depressing the key off-center, it is possible that the circular cental key area may not physically contact the electrical contact disposed below and thereby fail to provide an electrical coupling. Moreover, switches of the type disclosed by U.S. Pat. No. 3,979,568 are typically formed on a continuous metal sheet and have particular application for "sandwiched" type keyboards, and are not readily modified for use as discrete key switches.
As will be disclosed below, the present invention provides a simple, but highly reliable and cost effective, keyboard switch assembly with a unique tactile feel which overcomes the inherent disadvantages of prior art devices.